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Responsible Refrigeration No 73

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Responsible Refrigeration No 73

With the now ever increasing use of flammable refrigerants Practitioners must be very aware of the safety requirements when working on refrigeration units using these gases. This was mentioned in a previous article, I wonder who took the time to read this and absorb and understand the dangers.

We’ve been using non-flammable refrigerants since the 1930s and 1940s. They are now being phased out at a very fast pace. With the movement to Hydro Carbon refrigerants what are the new procedure and practices that must be followed by practitioners in handling flammable refrigerants?

Where are they being used?

First we see R290 used in domestic refrigerators and beverage coolers. Then R600ais also used in ice makers and refrigeration units. I was in the UK in November and saw an ice maker on a counter producing a dozen ice cubes every 7 minutes running on R600a. We are aware that room air conditioners are soon to be introduced that will be on R600a.

The same procedures and methods we use for the common refrigerants we use now will also apply to flammable A2L, A2 and A3 refrigerants. Do you remember in a previous column I gave the chart for the classification of refrigerants?  With refrigerants that are operating under pressure is why the Department of Employment and Labour introduced in July 2009 Pressure Equipment Regulations into the OHS Act. This is also why for safety reasons and compliance you’ve got to be a registered practitioner and be careful when you’re handling flammable refrigerants.

During transportation cylinders must be kept upright they and have to be secured properly in storage and during transportation.

The work zone when carrying out service and repair a 2 meter flame hazard zone in all directions of an outdoor condensing unit and if indoors from the refrigeration appliance. If the area is a confined space within a building like a plant room the area must be well ventilated. These are the same procedures that apply to the common refrigerants and will still apply to the 3 classification levels for flammable refrigerants.

Then there is the Refrigerant Concentration Limit (RCL), (ASHRAE standard 34 – 2019) this limit in air is determined in accordance with this standard and intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. This means the amount of refrigerant allowable in a space if there is leakage. With an A2L refrigerant like R32 which has a lower flammability the concentration can be calculated. The table below: from the United Nations Environment Program, Economy Division, Ozone Action and the Pacific Islands Countries Guide; shows recommended refrigerant charge for R32 in unit types in various positions and floor areas.

MAXIMUM ALLOWABLE CHARGE OF R-32 IN KILPGRAMS FOR AIR-CONDITIONING UNITS

FOR VARIUS POSITIONS INSTALLED

(KG)

AreaFloor mountedWindow mountedWall mountedCeiling mounted
Max Kg chargeMax Kg chargeMax Kg chargeMax Kg charge
91.031.713.093.77
121.191.983.564.35
151.332.23.984.87
181.452.424.365.33
211.572.624.715.76
241.682.805.046.16

Engineers, installers and servicing technician must ensure that the actual charge size of refrigerant in an air conditioning or refrigeration system being installed or serviced does not exceed the maximum charge size and must be aware of these limitations. The charge limits have increased from 150g to 500g for the most flammable A3 refrigerants. For mildly flammable alternatives (A2 and A2L), the limit has increased from 150g to 1.2kg. This was done in 2019 by the International Electrotechnical Commission (IEC) in the revised safety standard IEC 60335-2-89. The new higher limits only apply to some applications and only in rooms of a certain size as indicated in the table above.

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